Families in the U.S. spend $500 billion yearly on their adult children — two times the amount they put into retirement savings, a Merrill Lynch study shows.

According to a joint study from Merrill Lynch and Age Wave - an aging research group - of all the stages of parenting, the empty-nest stage is the most pricey. This stage occurs when their children are over the age of 18.

"Empty nesting offers the chance to reduce expenses, spend more on leisure and save more toward retirement," the report states. "However, those plans can get sidetracked when parents continue to serve as the ‘family bank’ for adult children."

The study was carried out in June 2018, asking 2,500 parents with children aged 18 and older questions about their current phase of parenting. Of the parents with adult children, more than 79% stated that they financially support their adult children — especially during their college years — with 72% saying that they put their children’s interest ahead of retirement savings.

"One-quarter of parents say they are willing to take on debt and pull money from retirement savings," the report stated. Some delay their retirement causing unhealthy stress to themselves and creating situations that could have had a minimal impact on the parent's quality of life had the parent just said no to continued financial support that they really cannot afford. Heather E., a wealth management advisor with Merrill Lynch, states that supporting adult children financially can spoil a retirement plan.

Just because the kids have moved out of the house doesn't mean they're out of the parent's financial life. Six out of 10 parents with at least one adult child over 18 said they provided them financial help, according to Pew Research Center survey.

Of the $500 billion tab, $54 billion yearly goes to groceries and food; and $18 billion to cell phone providers, which most times is paid in full. Parents also helped with school payments and car bills. The student loan "bubble and crisis" is contributing to this issue of adults needing financial help from their mothers and fathers. $500 billion total did not include other common costs, like weddings or contributions to first-home down payments.

"Today’s parents also frequently contribute toward adult children’s housing, car, and even vacation fees," the report said. For parents, this type of "behavioral bias" isn't unreasonable due to the fact that "the future is less certain" and parents are "around to enjoy it now" based on the viewpoint of Jame H. a professor of retirement planning at The American College of Financial Services

"Money and finances also are just a means to an end," he stated. "The end goal is our happiness, which often includes our family’s financial stability. If we save for retirement, but our children are unhappy today, we are also unlikely to enjoy our lives."

Many experts say it is vital to nudge kids along and make sure they are equipped to take the dive into financial independence. The quicker they can make the transition, the faster parents can free up much needed cash for goals such as boosting a retirement account, chipping away at debt or to have money for car and home repairs.

For parents to get their adult children financially confident, Heather E. said parents have to have tough love. "I think you have to sit down and have a heart-to-heart," she stated. "Look at the children’s expenses and give them a deadline."